2021年职称英语考试《理工类》考试共65题，分为单选题和多选题和判断题和计算题和简答题和不定项。小编每天为您准备了5道每日一练题目（附答案解析），一步一步陪你备考，每一次练习的成功，都会淋漓尽致的反映在分数上。一起加油前行。

1、AIDSAs a science writer, I don\'t have to wear emotional armor very often. Before I went to Zimbabwe for a visit, I had talked to other reporters who had spent time in Africa. All told me to get prepared for the orphans, many of whom had caught the AIDS virus from their mothers and the strong desire to make everything all right for them. Then again, nothing could have prepared me for the visit to creche(育婴堂) for AIDS orphans in Harare, where one sick, smiling four-year-old boy tried to keep up with the other kids playing ring-around-the-rosy but was so weak he kept falling to the floor, or meeting a 25-year-old unmarried girl who cared for her nephew ______ The boy who called his aunt "Mama" was too weak even to take the piece of banana I offered. Meanwhile photojournalist Karin Retief was visiting a room at the hospice (济贫院) where she had been told a particularly sweet orphan boy stayed. At first she did not see anyone on the bed and was about to say he must be elsewhere, when suddenly she spotted his tiny arm in the air, his body lost in the folds of the bedclothes. Recently Karin wrote to me that she had been able to keep our assignment from taking too great an emotional suffering at the time. " Only when I got back about a week later, could I moum the people I met", she continued. "I sat in church and wanted to ask the priest to pray for the people with AIDS in Zimbabwe and all over the world. Then all the people\'s faces, pain and suffering became so real, I could not get the words out. I broke down and cried and cried for them". 【单选题】

A.where she had been told a particularly sweet orphan boy stayed

B.who had spent time in Africa

C.Only when I got back about a week later

D.even though her only income was from growing and selling a few vegetables at the local market

E.was so weak he kept falling to the floor

F.while we were visiting the orphans

正确答案:D

答案解析:一个未婚女孩照顾她的侄子，尽管她的唯一收入来源是种菜，并在当地市场出售。符合语法要求，意思也完整。因此选D。

2、Radiocarbon DatingNowadays scientists can answer many questions about the past through a technique called radiocarbon (放射性碳), or carbon - 14 dating. One key to understanding how and why something happened is to discover when it happened.Radiocarbon dating was developed in the late 1940s by physicist Willard F. Libby at the University of Chicago. An atom of ordinary carbon, called carbon -12, has six protons (质子) and six neutrons (中子) in its nucleus (原子核). Carbon - 14, or C - 14, is a radioactive, unstable form of carbon that has two extra neutrons. It returns to a more stable form of carbon through a process called decay (衰减). This process involves the loss of the extra neutrons and energy from the nucleus.In Libby\'s radiocarbon dating technique, the weak radioactive emissions(放射)from this decay process are counted by instruments such as a radiation detector and counter. The decay rate is used to determine the proportion of C -14 atoms in the sample being dated.Carbon - 14 is produced in the Earth\'s atmosphere when nitrogen(氮) - 14, or N - 14, interacts with cosmic rays (宇宙射线). Scientists believe since the Earth was formed, the amount of nitrogen in the atmosphere has remained constant. Consequently, C -14 formation is thought to occur at a constant rate. Now the ratio of C -14 to other carbon atoms in the atmosphere is known. Most scientists agree that this ratio is useful for dating items back to at least 50,000 years.All life on Earth is made of organic molecules (分子) that contain carbon atoms coming from the atmosphere. So all living things have about the same ratio of C -14 atoms to other carbon atoms in their tissues (组织). Once an organism (有机体) dies it stops taking in carbon in any form, and the C -14 already present begins to decay. Over time the amount of C - 14 in the material decreases and the ratio of C - 14 to other carbon atoms goes down. In terms of radiocarbon dating, the fewer C -14 atoms in a sample, the older that sample is.The half - life of C - 14 is about 25 ,000 years.【单选题】

A.Right

B.Wrong

C.Not mentioned

正确答案:C

答案解析:本题有较大难度，答案依据不明显，需要通读全文作出判断。通读全文后可以发现文章并未提及碳的半衰期是25，000年，所以本题是未提及的，答案是C。

3、WaterThe second most important constituent (构成成份) of the biosphere (生物圈) is liquid water. This can only exist in a very narrow range of temperatures, since water freezes at 0℃ and boils at 100℃. Life as we know it would only be possible on the surface of a planet which had temperatures somewhere within this narrow range.The earth\'s supply of water probably remains fairly constant in quantity. The total quantity of water is not known very accurately, but it is about enough to cover the surface of the globe to a depth of about two and three - quarter kilometers. Most of it is in the form of the salt water of the oceans about 97 percent. The rest is fresh, but three -quarters of this is in the form of ice at the Poles and on mountains, and cannot be used by living systems until melted. Of the remaining fraction, which is somewhat less than one percent of the whole, there is 10 -20 times as much stored underground water as there is actually on the surface. There is also a tiny, but extremely important fraction of the water supply which is present as water vapour in the atmosphere.Water vapour in the atmosphere is the channel through which the whole water circulation (循环) of the biosphere has to pass. Water evaporated (蒸发) from the surface of the oceans, from lakes and rivers and from moist (潮湿的) earth is added to it. From it the water comes out again as rain or snow, falling on either the sea or the land. There is, as might be expected, a more intensive evaporation per unit area over the sea and oceans than over the land, but there is more rainfall over the land than over the oceans and the balance is restored by the runoff from the land in the form of rivers.Most of the flesh water on Earth ______.【单选题】

A.is stored underground

B.is in the form of ice at the Poles and on mountains

C.is found in rivers and lakes

D.comes from the rain

正确答案:B

答案解析:本题有一定难度，需要认真读懂文章句意，答案依据比较明显，在文章第二段第四句，谈到剩下1/3的淡水以冰的形式存在在南北两极和高山上，回来看选项，B项是其近义解释，所以正确，答案是B。

4、Cell Phones1. Believe it or not, cell phones have been around for over a quarter of a century. The first commercial cell phone system was developed by the Japanese in 1979, but cell phones have changed a lot since that time. The early cell phones were big and heavy but they have developed into small and light palm sized models. There are huge developments in their functions, too. We have had call forwarding, text messaging, answering services and hands - free use for years, but now there are new facilities, such as instant access to the Internet and receiving and sending photos.2. Cell phones have become very common in our lives. Recent statistics suggest one in three people on the planet now have cell phone, and most of them say they couldn\'t live without one, Cell phones are used in every area of our lives and have become a necessary tool, used for essential arrangements, social contact and business. It easier to call for help on the highway. It possible to keep in touch with people "on the move" when people are traveling.3. Cell phones have made communication easier and have reduced the need for family arguments f We can use cell phones to let our family know we\'ll be late or if there\'s a sudden change of plan or an emergency. Cell phones have eased the worries of millions of parents when their teenagers are out late. They can now contact their children at any time.4. This does not mean that cell phones are all good news. Cell phones have brought with them a number of new headaches for their owners. It costs a lot to replace stolen phones, It is becoming a frequent occurrence, and have you ever seen such a huge phone bills? More serious, however, Cell phones bring the potential health problem. There are fears that radiation from the phones may cause brain tumor(肿瘤). This may be a time bomb waiting to happen to younger people who have grown up with cell phones. They simply can\'t live without cell phones!Paragraph 5 ______【单选题】

A.Cell phones and the family

B.Commercial cell phone systems

C.Cell phones in everyday life

D.Cell phones for teenagers

E.History of cell phones

F.Problems with cell phones

正确答案:F

答案解析:本题难度不大，主旨句比较明显，就是第四段的第一句：这并不意味着手机带来的都是好消息。后面谈到了手机带来的问题，F项Problems with cell phones是本段主旨句的近义解释，是答案。

5、Cell Phone Lets Your Secret OutYour cell phone holds secrets about you. Besides the names and numbers that you\'ve programmed into it, traces of your DNA linger on the device, according to a new study.DNA is genetic material that appears in every cell. Like your fingerprint, your DNA is unique to you- because you have an identical twin. Scientists today routinely analyze DNA in blood, saliva, or hair left behind at the scene of a crime. The results often help detectives identify criminals and their victims. Your cell phone can reveal more about you than you might think.Meghan J. McFadden, a scientist at McMaster University in Hamilton, Ontario, heard about a crime in which the suspect bled onto a cell phone and later dropped the device. This made her wonder whether traces of DNA lingered on cell phones even when no blood was involved. So she and colleague Margaret Wallace of the City University of New York analyzed the flip open phones of 10 volunteers. They used swabs to collect invisible traces of the users from two parts of the phone: the outside, where the user holds it, and the ______, which is placed at the user\'s ear.The scientists scrubbed the phones using a solution made mostly of alcohol. The aim of washing was to remove all detectable traces of DNA. The owners got their phones back for another week. Then the researchers collected the phones and repeated the swabbing of each phone once more.The scientists discovered DNA that belonged to the phone\'s speaker on each of the phones. Better samples were collected from the outside of each phone, those swabs also picked up DNA that belonged to other people who had apparently also handled the phone. Surprisingly, DNA showed up even in swabs that were taken immediately after the phones were scrubbed. That suggests that washing won\'t remove all traces of evidence from a criminal\'s device. So cell phones can now be added to the list of clues that can clinch a crime scene investigation.【单选题】

A.card

B.keys

C.screen

D.speaker

正确答案:D

答案解析:研究者从手机的两部分收集手机微量DNA：一是手机外壳，二是喇叭。贴在耳朵上的不可能是card、screen和keys。